#pragma once

#include <types.h>
#include <virtio/virtio_ids.h>
#include <virtio/virtio_types.h>

/* Feature bits */
#define VIRTIO_BLK_F_SIZE_MAX 1      /* Indicates maximum segment size */
#define VIRTIO_BLK_F_SEG_MAX 2       /* Indicates maximum # of segments */
#define VIRTIO_BLK_F_GEOMETRY 4      /* Legacy geometry available  */
#define VIRTIO_BLK_F_RO 5            /* Disk is read-only */
#define VIRTIO_BLK_F_BLK_SIZE 6      /* Block size of disk is available*/
#define VIRTIO_BLK_F_TOPOLOGY 10     /* Topology information is available */
#define VIRTIO_BLK_F_MQ 12           /* support more than one vq */
#define VIRTIO_BLK_F_DISCARD 13      /* DISCARD is supported */
#define VIRTIO_BLK_F_WRITE_ZEROES 14 /* WRITE ZEROES is supported */

/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
#define VIRTIO_BLK_F_BARRIER 0     /* Does host support barriers? */
#define VIRTIO_BLK_F_SCSI 7        /* Supports scsi command passthru */
#define VIRTIO_BLK_F_FLUSH 9       /* Flush command supported */
#define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */
/* Old (deprecated) name for VIRTIO_BLK_F_FLUSH. */
#define VIRTIO_BLK_F_WCE VIRTIO_BLK_F_FLUSH
#endif /* !VIRTIO_BLK_NO_LEGACY */

#define VIRTIO_BLK_ID_BYTES 20 /* ID string length */

struct virtio_blk_config
{
    /* The capacity (in 512-byte sectors). */
    __virtio64 capacity;
    /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
    __virtio32 size_max;
    /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
    __virtio32 seg_max;
    /* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
    struct virtio_blk_geometry
    {
        __virtio16 cylinders;
        uint8_t heads;
        uint8_t sectors;
    } geometry;

    /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
    __virtio32 blk_size;

    /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
    /* exponent for physical block per logical block. */
    uint8_t physical_block_exp;
    /* alignment offset in logical blocks. */
    uint8_t alignment_offset;
    /* minimum I/O size without performance penalty in logical blocks. */
    __virtio16 min_io_size;
    /* optimal sustained I/O size in logical blocks. */
    __virtio32 opt_io_size;

    /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
    uint8_t wce;
    uint8_t unused;

    /* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
    __virtio16 num_queues;

    /* the next 3 entries are guarded by VIRTIO_BLK_F_DISCARD */
    /*
	 * The maximum discard sectors (in 512-byte sectors) for
	 * one segment.
	 */
    __virtio32 max_discard_sectors;
    /*
	 * The maximum number of discard segments in a
	 * discard command.
	 */
    __virtio32 max_discard_seg;
    /* Discard commands must be aligned to this number of sectors. */
    __virtio32 discard_sector_alignment;

    /* the next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES */
    /*
	 * The maximum number of write zeroes sectors (in 512-byte sectors) in
	 * one segment.
	 */
    __virtio32 max_write_zeroes_sectors;
    /*
	 * The maximum number of segments in a write zeroes
	 * command.
	 */
    __virtio32 max_write_zeroes_seg;
    /*
	 * Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
	 * deallocation of one or more of the sectors.
	 */
    uint8_t write_zeroes_may_unmap;

    uint8_t unused1[3];
} __attribute__((packed));

/*
 * Command types
 *
 * Usage is a bit tricky as some bits are used as flags and some are not.
 *
 * Rules:
 *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
 *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
 *   and may not be combined with any of the other flags.
 */

/* These two define direction. */
#define VIRTIO_BLK_T_IN 0
#define VIRTIO_BLK_T_OUT 1

#ifndef VIRTIO_BLK_NO_LEGACY
/* This bit says it's a scsi command, not an actual read or write. */
#define VIRTIO_BLK_T_SCSI_CMD 2
#endif /* VIRTIO_BLK_NO_LEGACY */

/* Cache flush command */
#define VIRTIO_BLK_T_FLUSH 4

/* Get device ID command */
#define VIRTIO_BLK_T_GET_ID 8

/* Discard command */
#define VIRTIO_BLK_T_DISCARD 11

/* Write zeroes command */
#define VIRTIO_BLK_T_WRITE_ZEROES 13

#ifndef VIRTIO_BLK_NO_LEGACY
/* Barrier before this op. */
#define VIRTIO_BLK_T_BARRIER 0x80000000
#endif /* !VIRTIO_BLK_NO_LEGACY */

/*
 * This comes first in the read scatter-gather list.
 * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
 * this is the first element of the read scatter-gather list.
 */
struct virtio_blk_outhdr
{
    /* VIRTIO_BLK_T* */
    __virtio32 type;
    /* io priority. */
    __virtio32 ioprio;
    /* Sector (ie. 512 byte offset) */
    __virtio64 sector;
};

/* Unmap this range (only valid for write zeroes command) */
#define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP 0x00000001

/* Discard/write zeroes range for each request. */
struct virtio_blk_discard_write_zeroes
{
    /* discard/write zeroes start sector */
    uint64_t sector;
    /* number of discard/write zeroes sectors */
    uint32_t num_sectors;
    /* flags for this range */
    uint32_t flags;
};

#ifndef VIRTIO_BLK_NO_LEGACY
struct virtio_scsi_inhdr
{
    __virtio32 errors;
    __virtio32 data_len;
    __virtio32 sense_len;
    __virtio32 residual;
};
#endif /* !VIRTIO_BLK_NO_LEGACY */

/* And this is the final byte of the write scatter-gather list. */
#define VIRTIO_BLK_S_OK 0
#define VIRTIO_BLK_S_IOERR 1
#define VIRTIO_BLK_S_UNSUPP 2